1. Field of the Invention
This invention relates to packaging devices, and in particular, to impact-resistent and impact-absorbing packaging devices for protecting an article contained therein.
2. Description of the Prior Art
The shipment and storage of articles which require special handling (e.g., fragile articles) has long plagued the packaging industry. Loose fill, such as shredded newspapers or foam beads (i.e., "peanuts"), have been tried as a means to protect article in a container, but such loose fill still allows shifting of the article in the container, and does not provide an affirmative cradling or nesting for the article in the container. Another attempt to solve this problem is to use premolded, form-fitting foam or other impact absorbing shells which are designed to encapsulate the article within some other container. Of course, the problem with this approach is that the shells must be preformed and designed specifically for the article to be stored or shipped.
One other approach to this problem has been the development of expandable or inflatable cushions mounted within a container. The article to be protected is placed between one or more of such cushions and the cushion expanded to envelope the article. In its expanded state, the material is impact absorbing and thereby shields the article from direct impact forces acting on the container, such as if the container were dropped. Such cushions have taken the form of simple inflatable air bladders, or expandable foam.
Examples of impact absorbing packaging devices using such an expandable foam material are shown in Lookholder U.S. Pat. No. 4,193,499 and Lookholder U.S. Pat. No. 4,620,633, both of which are incorporated by reference herein. In the Lookholder '499 patent, the article is placed in an envelope-like container which is, at least in part, surrounded by expandable material. The expandable material is a mixture of polystyrene beads and a blowing agent sealed within an air-tight pouch. To expand this polystyrene bead mixture and make it impact-absorbing, the mixture is exposed to microwave radiation. In the Lookholder '633 patent, the container is essentially the same, but the expandable material is a slab of compressed open-celled cellular material such as synthetic foam. The material is hermetically sealed in a pouch in its initial compressed state, and the pouch is held in a reduced atmospheric pressure condition to maintain the cellular material in its compressed state (no air within its open cells). To expand the material, the pouch is breached to raise its pressure to that of atmospheric pressure, which allows air into the interstices of the open-celled cellular material, thereby expanding the material to provide a cushion for the article retained in the envelope between expanded layers of the foam material.
The compressed foam approach of the Lookholder '633 patent is quite useful and simple in creating an easy to use, relatively efficient impact-absorbing packaging container for a article that requires special handling. While this packaging container does provide some protection for an article placed therein, it is still desired to provide a packaging container which has the ability not only to absorb impact forces, but also to resist them and spread them out across the surface of the package, so as to better protect the article therein.